Adoptionism

Adoptionism, a heretical doctrine akin to Nestorianism, originated about the end of the 8th century in Spain. Elipandus, Archbishop of Toledo, and Felix, the Bishop of Urgel, advanced the opinion that Christ, in respect of his divine nature, was doubtless the Son of God; but that as to his human nature, he was only declared and adopted to be the first-born Son of God. The flame of controversy thus kindled, spread into the Frankish empire, and gave occasion to three synods, one held at Ratisbon (792), another at Frankfurt (794), and a third at Aix-la-Chapelle (799). Adoptionism was condemned as heresy, and the Catholic doctrine of the unity of the two natures of Christ in one divine person was re-affirmed.